QUuid: add a named fromUInt128() ctor

This makes the API symmetric again (fromBytes()/toBytes(),
fromString()/toString(), fromUInt128()/toUInt128()), but also gives us
the option to remove the QUuid(quint128), should we so choose, because
of its overly-broad argument matching range.

Found in API review.

Change-Id: I91bd2450d62ed565ec3b8e46c875f4983bd9dc73
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 70835a93351b3288a8df4361e648b9cd951ad436)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/plugin/quuid.cpp

@@ -320,6 +320,19 @@ static QUuid createFromName(const QUuid &ns, const QByteArray &baseData, QCrypto
     \note This function is only present on platforms that offer a 128-bit
     integer type.
 
+    \sa toUInt128(), fromUInt128(), fromBytes(), toBytes(), toRfc4122()
+*/
+
+/*!
+    \fn QUuid::fromUInt128(quint128 uuid, QSysInfo::Endian order) noexcept
+    \since 6.6
+
+    Creates a QUuid based on the integral \a uuid parameter and respecting the
+    byte order \a order.
+
+    \note This function is only present on platforms that offer a 128-bit
+    integer type.
+
     \sa toUInt128(), fromBytes(), toBytes(), toRfc4122()
 */
 
@@ -335,7 +348,7 @@ static QUuid createFromName(const QUuid &ns, const QByteArray &baseData, QCrypto
     \note This function is only present on platforms that offer a 128-bit
     integer type.
 
-    \sa toRfc4122(), toBytes(), fromBytes(), QUuid()
+    \sa toRfc4122(), fromUInt128(), toBytes(), fromBytes(), QUuid()
 */
 
 /*!

src/corelib/plugin/quuid.h

@@ -102,6 +102,8 @@ public:
 
 #ifdef QT_SUPPORTS_INT128
     constexpr explicit QUuid(quint128 uuid, QSysInfo::Endian order = QSysInfo::BigEndian) noexcept;
+    static constexpr QUuid fromUInt128(quint128 uuid, QSysInfo::Endian order = QSysInfo::BigEndian) noexcept
+    { return QUuid{uuid, order}; }
     constexpr quint128 toUInt128(QSysInfo::Endian order = QSysInfo::BigEndian) const noexcept;
 #endif